U.S. Pat. No. 6,034,470 B1 discloses a flat lamp having electrode tracks arranged on the inner side of a discharge vessel wall, which is installed for the purpose of backlighting an LCD monitor in a common housing (see FIG. 7). However, no details are given on fixing the flat lamp within the housing. It can merely be seen in FIG. 7 that the flat lamp is, as it were, “clamped in” between the side walls of the housing at a certain spacing from the rear wall of said housing. A general problem in the case of backlighting LCDs consists in the fact that flat lamps produce, during operation, undesirable heat emissions, but the LCDs are relatively sensitive to high temperatures, which makes necessary correspondingly effective thermal management. For this purpose, U.S. Pat. No. 6,034,470 B1 proposes attaching a cooling body to the outer side of the rear wall of the housing. However, no details are given on the transportation of heat from the flat lamp to the housing rear wall.